textproduct: Rapid City

KEY MESSAGES

- Isolated strong/severe thunderstorms possible through early this evening - Southwest flow aloft expected through the weekend with showers/thunderstorms possible late Thursday/Friday - Upper trough moves through for early next week bring increasing precipitation chances Sunday night into early next week - Temperatures will be 5-10F above normal through the weekend and then back to seasonal readings early next week

DISCUSSION

(This Evening Through Wednesday) Issued at 100 PM MDT Wed Sep 23 2026

18z surface analysis had warm front from weak low over southeast MT into eastern CO. Ahead of it, quite a bit of cloud cover persists. Behind it, clearing skies per 0.5km visible satellite loop. These features in association with shortwave trough moving across eastern MT/western ND per water vapour loop. 90kt streak overhead. Effects of these features the main short term forecast concern.

Later this afternoon/evening, early Fall solar insolation should erase MLCIN from the 18z KUDX sounding with surface temperatures around 80F needed. ~1KJ/kg MLCAPE will be available along the warm front with 40kts of effective shear under jet streak. Convection should develop after 21z per most CAMs with isolated strong/severe thunderstorms possible creating marginally severe hail/wind gusts. Activity will move east this evening with clearing skies over the CWA overnight. Temperatures will be near guidance.

Shortwave ridging Thursday will bring dry weather for most of the CWA, but aforementioned warm front gets hung up over the SD/NE border which may be the focus for a few shra/TS. Stronger wave arrives Friday with increasing PoPs, especially east of the Black Hills where best low level moisture return/buoyancy forecast. Dry Saturday and most of Sunday. Temperatures will be 5-10F above normal through the weekend. Then, ensemble guidance portrays a strong upper trough slicing across the northern Plains with increasing chances of precipitation as well as cooler, more fall- like temperatures.

AVIATION

(For the 00Z TAFS Through 00Z Friday) Issued At 613 PM MDT Wed Sep 23 2026

A few showers and strong thunderstorms are in progress this evening from the northern Black Hills northeast across the northwestern South Dakota plains, with the potential for brief drops to IFR cigs and MVFR vsbys, hail, and gusty/erratic winds as high as 50kts as they translate eastward. Potential back to the southwest as KRAP and KGCC is too low to warrant PROB30s. A few additional, weaker showers and storms will be possible across the south-central South Dakota plains as well. High-res guidance generally clears all of this activity out of the region by 06z tonight, except perhaps KICR. Outside of storms, VFR conditions are expected are expected throughout the forecast period into Thursday (high confidence from mid-morning Thursday onward). RH values will be a bit moist overnight tonight across our plains east of the Black Hills, but at this time there is little to no support in the guidance for any broad development of fog or low stratus. Thursday night, south/southeast winds will increase and become a bit gusty at KGCC...just beyond the end of the current TAF period.

UNR WATCHES/WARNINGS/ADVISORIES

SD...None. WY...None.